1. Field of the Invention
The present invention relates to a projection apparatus, a projection method, and a storage medium having program stored thereon, suitable for a projector using a pointing device.
2. Description of the Related Art
The technique for enabling a virtual image to be drawn on a projection image or a projection image to be pointed at with a pointing device (or a special pointing pen) in a DLP (Digital Light Processing) (a registered trademark) projector has been put to practical use.
This type of pointing pen reads invisible coordinate information modulated and superimposed on a projection image and transmits its position information to a projector body wirelessly.
Having received the position information, the projector transmits the information to an external device that is supplying an image signal, for example, a personal computer (hereinafter, referred to as a PC), thereby performing necessary writing on an image output to be projected on an application of the PC.
In a case where processing is performed with a plurality at screens being opened in multitasking on the PC that supplies images in a projection environment using the pointing pen, when images are being projected by, for example, the PC transmitting an image signal of a secondary screen to the projector, the PC, having received position information on the pointing pen via the projector, might create, on a primary screen, not on the secondary screen, an image in which the position information on the pointing pen has been reflected.
FIG. 5 shows the aforementioned projection system.
In FIG. 5, numeral 1 indicates a projector and numeral 2 indicates a PC that supplies to the projector 1 an image to be projected.
The projector 1 and PC 2 are connected to each other with a VGA cable VC and a USB cable UC.
The PC 2 supplies an image signal to the projector 1 via the VGA cable VC. The projector 1 projects, on a screen, a projection image PI according to the image signal.
Numeral 3 indicates a dedicated pointing pen for the projector 1. The projector 1 and pointing pen 3 are connected wirelessly by, for example, Bluetooth (a registered trademark) technology.
A projection image PI projected by the projector 1 is formed such that position coordinate information a invisible to the naked eye has been superimposed on an original image.
The pointing pen 3 includes a light-receiving system and a demodulating circuit for the position coordinate signal, thereby pointing at an arbitrary position in the projection image PI, demodulating the position coordinate signal in the pointed-at position, and transmitting the demodulated signal as pointed-at coordinate information to the projector 1.
Having received the information, the projector 1 transmits the coordinate information to the PC 2.
FIG. 6 shows a primary screen and a secondary screen on an application run on the PC 2, respectively.
When the PC 2 has been supplying an image signal of the secondary screen to the projector 1 via the VGA cable VC, the PC 2, having received the pointed-at coordinate information from the projector 1 via the USB cable UC, superimposes an image of a pointer PT corresponding to the pointing on the primary screen, not on the secondary screen, as shown in FIG. 6.
Therefore, the image of the pointer PT has not been reflected in the image signal of the secondary screen transmitted by the PC 2 to the projector 1, with the result that the pointer PT is not projected on the projection image PI.